> I don’t mean it in the sense of software dependencies, but in the sense that some app you use would compromise you. You know macOS’ permissions are mostly security theatre. We know people inside Apple use third-party apps. I can imagine ways of exploiting that, given a bit more knowledge of people from inside (which could be gathered from working there for a while, trawling social media, maybe reading Gruber’s emails, …).
You seem to be waffling here between targeted and untargeted attacks.
There's a world of difference between compromising me or an Apple employee and compromising my software or Apple's software. You don't magically get the latter from the former.
Untargeted attacks are just looking for the usual stuff, e.g., money. They don't care about who the victims are or what else they have.
It would require a targeted attack to insert mallicious code into my software or into Apple's software. You claim, "I can imagine ways of exploiting that," but I don't actually believe you. If you can imagine it, then explain exactly how.
There's no evidence that anyone is targeting my software or that anyone has any reason to target my software. Even if I downloaded a typical malware app from the web, that wouldn't result in malicious code getting shipped in my software.
I'm not aware of anyone on the Apple Passwords team using my software, so if someone were trying to attack me to get to them, that's seems a bit fruitless, to use a pun. In any case, the chain from compromising me, to compromising my software releases, to compromising an Apple engineer, to compromising Apple software releases, is convoluted to the extreme and would require much more specifics than anyone has given here (or is capable of giving).
In any case, I'm quite careful—though not tin foil hat paranoid—about which software I download and run on my Mac, and I've never downloaded malware in more than 20 years as a Mac user. Obviously I'm careful about my own privacy and security, since I use Little Snitch too!